This is the original book on differential games. It is as relevant today as when it was written nearly 40 years ago. The book introduces all the main concepts and equations in differential games. This is achieved without recourse to heavy theorems or proofs. A central feature is the use of many and varied examples of differential games; the homoicidal chauffeur, wars of attrition, pursuit with a rocket, etc. These bring the whole field alive with potential. Another element is the use of geometry and pictures to describe game evolution. This book is a must for anyone interested in modern autonomous systems.